package main

import "fmt"

// MAX 是数字数量
const MAX = 1000

func main() {
	f1, f2 := make([]int, MAX), make([]int, MAX)
	f1[0], f2[0] = 1, 1
	for i := 3; ; i++ {
		f3 := make([]int, MAX)
		for j := 0; j < MAX-1; j++ {
			f3[j] += f1[j] + f2[j]
			if f3[j] > 9 {
				f3[j+1] += f3[j] / 10
				f3[j] %= 10
			}
		}
		if f3[MAX-1] > 0 {
			fmt.Println(i)
			break
		}
		f1, f2 = f2, f3
	}
}
